Positive-working chemical-amplification photoresist composition

Abstract

Disclosed is a novel positive-working chemical-amplification photoresist composition capable of giving an extremely finely patterned resist layer in the manufacturing process of semiconductor devices. The photoresist composition comprises: (A) 100 parts by weight of a copolymeric resin consisting of from 50 to 85% by moles of (a) hydroxyl group-containing styrene units, from 15 to 35% by moles of (b) styrene units and from 2 to 20% by moles of (c) acrylate or methacrylate ester units each having a solubility-reducing group capable of being eliminated in the presence of an acid; and (B) from 1 to 20 parts by weight of a radiation-sensitive acid-generating agent which is an onium salt containing a fluoroalkyl sulfonate ion having 3 to 10 carbon atoms as the anion such as bis(4-tert-butylphenyl) iodonium nonafluorobutane sulfonate.

What is claimed is:  
     
       1. A resin composition which is a combination of two resinous compounds comprising: 
       a first copolymeric resin consisting of from 62 to 68% by moles of the monomeric units (a) hydroxyl group-containing styrene units, from 15 to 25% by moles of the monomeric units (b) styrene units and from 12 to 18% by moles of the monomeric units (c) acrylate or methacrylate ester units each having a tertiary alkyl solubility-reducing group capable of being eliminated in the presence of an acid and  
       a second copolymeric resin consisting of from 62 to 68% by moles of the monomeric units (a), from 25 to 35% by moles of the monomeric units (b) and from 2 to 8% by moles of the monomeric units (c), in a weight ratio in the range from 9:1 to 5:5.  
     
     
       2. The resin composition according to  claim 1  in which the weight proportion of the first copolymeric resin to the second copolymeric resin is within the range of from 8:2 to 6:4. 
     
     
       3. The resin composition according to  claim 1  wherein the tertiary alkyl group is a tert-butyl group.